My engine will rev up on it's own when I start the car. it will sustain about 2000 rpm for a few seconds then calm down to a normal Idol. If I rev it up to about 2000 after that, it will come down to about 1250 rmp then back up to 2000, back down to 1000 then up to 1750, it will alternate like this a few more times before calming down to a normal idol at about 800 rpm. What in the world could be causing this?

 

SES light? Possibles : vacuum leak(s),bad tps,unlearned idle,ground problem.Hope it helps